[PATCH] rust: bindings: add `rust_helper_wait_for_completion` helper function

[Guangbo Cui]

> -extern void wait_for_completion(struct completion *);
> -extern void wait_for_completion_io(struct completion *);
> -extern int wait_for_completion_interruptible(struct completion *x);
> -extern int wait_for_completion_killable(struct completion *x);
> -extern int wait_for_completion_state(struct completion *x, unsigned int state);
> -extern unsigned long wait_for_completion_timeout(struct completion *x,
> +extern void __wait_for_completion(struct completion *);
> +extern void __wait_for_completion_io(struct completion *);
> +extern int __wait_for_completion_interruptible(struct completion *x);
> +extern int __wait_for_completion_killable(struct completion *x);
> +extern int __wait_for_completion_state(struct completion *x, unsigned int state);
> +extern unsigned long __wait_for_completion_timeout(struct completion *x,
>  						   unsigned long timeout);
> -extern unsigned long wait_for_completion_io_timeout(struct completion *x,
> +extern unsigned long __wait_for_completion_io_timeout(struct completion *x,
>  						    unsigned long timeout);
> -extern long wait_for_completion_interruptible_timeout(
> +extern long __wait_for_completion_interruptible_timeout(
>  	struct completion *x, unsigned long timeout);
> -extern long wait_for_completion_killable_timeout(
> +extern long __wait_for_completion_killable_timeout(
>  	struct completion *x, unsigned long timeout);
>  extern bool try_wait_for_completion(struct completion *x);
>  extern bool completion_done(struct completion *x);
> @@ -139,4 +134,79 @@ extern void complete(struct completion *);
>  extern void complete_on_current_cpu(struct completion *x);
>  extern void complete_all(struct completion *);
>  
> +#define wait_for_completion(x)						\
> +({									\
> +	sdt_might_sleep_start_timeout(NULL, -1L);			\
> +	__wait_for_completion(x);					\
> +	sdt_might_sleep_end();						\
> +})

The DEPT patch series changed `wait_for_completion` into a macro.
Because bindgen cannot handle function-like macros, this caused
Rust build errors. Add a helper function to fix it.

```
error[E0425]: cannot find function `wait_for_completion` in crate `bindings`
     --> rust/kernel/sync/completion.rs:110:28
      |
  110 |         unsafe { bindings::wait_for_completion(self.as_raw()) };
      |                            ^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `__wait_for_completion`
      |
     ::: /root/linux/rust/bindings/bindings_generated.rs:33440:5
      |
33440 |     pub fn __wait_for_completion(arg1: *mut completion);
      |     ---------------------------------------------------- similarly named function `__wait_for_completion` defined here

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0425`.
```

Signed-off-by: Guangbo Cui <2407018371@xxxxxx>
---
 rust/helpers/completion.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/rust/helpers/completion.c b/rust/helpers/completion.c
index b2443262a2ae..5bae5e749def 100644
--- a/rust/helpers/completion.c
+++ b/rust/helpers/completion.c
@@ -6,3 +6,8 @@ void rust_helper_init_completion(struct completion *x)
 {
 	init_completion(x);
 }
+
+void rust_helper_wait_for_completion(struct completion *x)
+{
+	wait_for_completion(x);
+}
-- 
2.43.0